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New NSA-Approved Encryption Standard May Contain Backdoor
Hugh Pickens writes "Bruce Schneier has a story on Wired about the new official standard for random-number generators the NIST released this year that will likely be followed by software and hardware developers around the world. There are four different approved techniques (pdf), called DRBGs, or 'Deterministic Random Bit Generators' based on existing cryptographic primitives. One is based on hash functions, one on HMAC, one on block ciphers and one on elliptic curves. The generator based on elliptic curves called Dual_EC_DRBG has been championed by the NSA and contains a weakness that can only be described as a backdoor. In a presentation at the CRYPTO 2007 conference (pdf) in August, Dan Shumow and Niels Ferguson showed that there are constants in the standard used to define the algorithm's elliptic curve that have a relationship with a second, secret set of numbers that can act as a kind of skeleton key. If you know the secret numbers, you can completely break any instantiation of Dual_EC_DRBG."
But this is the NSA we're talking about... Not the Bush administration.
Nothing in the world is more dangerous than sincere ignorance and conscientious stupidity.
How do you back door an Open algorithm you didn't design and don't distribute?
Nothing in the world is more dangerous than sincere ignorance and conscientious stupidity.
"Flyin' in just a sweet place,
Never been known to fail..."
The NSA is spying on all telecom signals passing through the US (including this message. Hi, Dick Cheney!). Despite the Constitution's prohibitions. Why would you trust them not to make your crypto crackable?
This situation shows one of the strongest arguments for open source. Trust no one.
--
make install -not war
More to the point, anyone else remember the premise of that movie? That said black box was utterly useless for doing anything other then spying on Americans, which (prior to Dubya anyway) was outside of the NSAs mandate.
I want peace on earth and goodwill toward man.
We are the United States Government! We don't do that sort of thing.
If I can predict the value of a symmetric key, or the value whose two factors constitute an asymmetric key pair, I have effectively broken the encryption. Even supposing that I can't do this deterministically, but merely somewhat better than random, I'm still that much further ahead.
Parity: What to do when the weekend comes.
So, if the NSA was indeed intentionally creating a backdoor, then they were doing a disservice to the "national security" they are supposedly protecting. By allowing (encouraging, in fact) top-secret government data to be encrypted in this way, they would be making the nation's secrets quite vulnerable. By comparison, private citizens and corporations can use whatever encryption they like, regardless of NSA recommendations.
I suppose one could argue that the NSA thought that no one would figure it out, so that they (and they alone) would be able to break that encryption for all time (so that they can spy on other branches of the government?). I think a simpler explanation is that NSA just made a mistake in endorsing that algorithm, and never intended to threaten national security. Of course it will be interesting to see what position they take now that a flaw has been publicly identified.
It's not the same thing. For a start, it's not even necessarily software. It's a mathematical algorithm.
So, yes, the implementation can be buggy, but for something like cryptography you'd at least expect the maths behind it to be rock-solid.
A lot of cryptography is based on stuff like that it's _far_ easier to multiply two prime numbers, than to find out which two large primes are the factors of a very large number. (I don't know this particular algorithm in TFA yet, so I used RSA as a simple example.) Once some maths guy has figured that out, and how it can be used, then the actual implementation in software tends to be actually very simple and straightforward. You just do one operation over and over again to encrypt the stuff, and another operation again and again to decrypt it. So even an error in the implementation is pretty inexcusable, because it's not a lot of code and you have a step-by-step description of exactly what to do.
Usually when an error in the implementation happens, it's not as much a programming bug, as the fact that (again) someone didn't understand the underlying maths and principles. E.g., I vaguely remember a disk encryption program which used a secure algorithm, but... had an invariable and huge block of known text at the beginning of it, which meant it was crackable anyway.
Anyway, to get back to the important part: it's not software, it's maths. Pure old-fashioned maths.
And... well, I'm not saying that that maths is easy. The average code monkey trying to invent encryption _will_ come with something ridiculously easy to crack.
But I'll say this: if the best and brightest mathematicians the NSA can find, still aren't competent enough, then I'd worry about the USA. I'm not even an American, and my attitude is somewhat anti-American (or at least anti-Bush), but even I in my crankiest hour wouldn't have _that_ bad an opinion of the USA.
To put it in perspective: something like this isn't like your average piece of code that someone typed on a Friday afternoon and never bothered to test. Something like this is bound to be reviewed by at least 2-3 other pairs of eyes before it becomes an official spec. So if they simply couldn't find anyone qualified enough to review it... I'd worry. A lot.
The conspiracy theory there is actually the _far_ more flattering alternative.
A polar bear is a cartesian bear after a coordinate transform.
Well I'm not surprised. Microsoft Research has tons of sharp security guys working there. Niels Ferguson is quite well-known in security circles. You don't get your company's name as an "author" unless your employees actually did the work; funding is not good enough. It might annoy the NSA, but academics don't care that much.
Don't tolerate incompetence.
Especially when the party involved should know better, and when there's a lot at stake.
- First they ignore you, then they laugh at you, then ???, then profit.
starfishsystems gives a good answer, but I'll say it a bit differently in case it helps.
The random number generator in question is a mathematical tool for generating randomness, not a cryptosystem of any kind. It has many potential applications. However, modern cryptography is absolutely dependent on high-quality randomness, so cryptosystems tend to use exactly this sort of tool. The thing is, if the "random" data stream one uses in a cryptosystem is actually predictable, then the whole cryptosystem is insecure right from the start no matter how good it otherwise appears.
It's is very much analagous to building a house on sand: if the foundation is unstable, it pretty much doesn't matter how good the rest of the construction on top of it may be; the whole structure is in dire and immediate peril.
The random number generator itself may be just fine for many applications. However, any cryptosystem built on this random number generator is presumed to be useless just because there exists a set of keys which can easily predict the whole random number stream given a tiny part of it. We don't actually know if anyone holds the keys, but if someone does then that person could undetectably open any cryptographic locks built on this random number generator, or release the keys so everyone could open the locks.
That help?
With reasonable men I will reason; with humane men I will plead; but to tyrants I will give no quarter. -- William Lloyd
It's somewhat surprising that an algorithm with a documented flaw made it through to the standard, but Schneier makes it clear that the NSA pressured NIST to let it through, so there are grounds for concern.
One swallow does not a fellatrix make